========= Implementace DKIM do postfixu =============
  sudo apt-get install opendkim opendkim-tools

do /etc/opendkim.conf
  AutoRestart             Yes
  AutoRestartRate         10/1h
  UMask                   002
  Syslog                  yes
  SyslogSuccess           Yes
  LogWhy                  Yes
  
  Canonicalization        relaxed/simple
  
  ExternalIgnoreList      refile:/etc/opendkim/TrustedHosts
  InternalHosts           refile:/etc/opendkim/TrustedHosts
  KeyTable                refile:/etc/opendkim/KeyTable
  SigningTable            refile:/etc/opendkim/SigningTable
  
  Mode                    sv
  PidFile                 /var/run/opendkim/opendkim.pid
  SignatureAlgorithm      rsa-sha256
  
  UserID                  opendkim:opendkim
  
  Socket                  inet:12301@localhost

do /etc/default/opendkim odkomentovat
  SOCKET="inet:12301@localhost"


Do postfixu pridat miltery, /etc/postfix/main.cf
  milter_protocol = 2
  milter_default_action = accept

Dalsi tam bud jsou, takze pridame
  smtpd_milters = unix:/spamass/spamass.sock, inet:localhost:12301
  non_smtpd_milters = unix:/spamass/spamass.sock, inet:localhost:12301

Nebo nejsou, takze vytvorime
  smtpd_milters = inet:localhost:12301
  non_smtpd_milters = inet:localhost:12301

  mkdir -p /etc/opendkim/keys
  
do /etc/opendkim/TrustedHosts
<code>
  127.0.0.1
  localhost
  192.168.0.1/24
  
  *.domena.com
</code>
do  /etc/opendkim/KeyTable
  nejakystring._domainkey.domena.com domena.com:nejakystring:/etc/opendkim/keys/domena.com/nejakystring.private
  
nejakystring je selector, libovolny.

do  /etc/opendkim/SigningTable
<code>
  *@domena.com nejakystring._domainkey.domena.com
</code>
  cd /etc/opendkim/keys
  mkdir domena.com
  cd domena.com

  opendkim-genkey -s nejakystring -d domena.com -b 2048
  chown opendkim:opendkim nejakystring.private
  
Z nejakystring.txt vzit "v=DKIM1; k=rsa; p=MIGf...." a pridat do DNS jako TXT zaznam. Pak reload DNS, postixu a opendkim a melo by to jet. Konotrla v logu nebo hlavicce.